The present invention relates to a parking brake device for a utility vehicle having at least one control valve device, having at least one relay valve, having at least one pneumatic brake device and having at least one trailer control module, wherein the relay valve is controllable by means of the control valve device, and wherein at least the pneumatic brake device is activatable by means of the relay valve.
Parking brakes of utility vehicles including trailers and rail vehicles are regularly nowadays provided with spring brake actuators which, in the release position, subject a spring compression space to compressed air and thereby keep the spring tensioned, while, for braking when parking, the spring compression space is vented, i.e. is connected to atmospheric pressure, and thus the brake actuator generates a braking force under the action of the spring (cf. Bosch, Kraftfahrtechnisches Taschenbuch [Automotive pocket book], 22nd edition, Dusseldorf, 1995, page 648).
Purely pneumatically operated parking brakes which are operated by generally bistable parking brake valves to be actuated by the driver, and electro-pneumatic systems having a bistable electromechanical valve which is controlled by an electromechanical bistable solenoid valve, are known. The two valve positions for “parking brake” and “release” have to be “stable” here, i.e. remain in the respectively selected position without action of a person. The same also applies to a failure of an electrical current supply for the solenoid valves.
DE 10 2009 059 816 A1 has already disclosed a parking brake device of the type in question for motor vehicles, in which the trailer control modules are arranged in the region of the control lines to the service brake of the motor vehicle.
The varying behavior of the electric parking brake depending on the vehicle-specifically differing lengths of tubing from the control space to the trailer control modules is a disadvantage of the previous prior art.
DE 10 2013 006 860 A1 has furthermore disclosed a pneumatic system for motor vehicles, in which, for example in conjunction with a parking brake device of the type in question, a solenoid valve for preparation of the air is also used at the same time for realizing what is referred to as a trailer test function for activating a trailer control module.
Since the line length to the trailer control valve varies in different types of vehicle, the volume of the control line for the electronic parking brake can therefore also be subject to said fluctuations. There can therefore be a small volume of the control line, which results in a rapid buildup of pressure and dissipation of pressure in the control line. If, however, there is a large volume of the control line, a slower buildup of pressure and dissipation of pressure in the control line arises. The regulation behavior of the electronic parking brake is therefore complicated and difficult to coordinate in order to ensure satisfactory operation.
It is therefore the object of the present invention to develop a parking brake device for a utility vehicle of the type mentioned at the beginning in an advantageous manner, in particular to the effect that the regulation behavior of a parking brake device, in particular of an electronic parking brake, can be configured so as to be able to be coordinated more simply and so as to be able to be adjusted more easily, and also, furthermore, the activation of the trailer and of the brake device thereof can be configured more simply.
This object is achieved according to the invention by a parking brake device for a utility vehicle having at least one control valve device, having at least one relay valve, having at least one pneumatic brake device and having at least one trailer control module, wherein the relay valve is controllable by the control valve device, and wherein at least the pneumatic brake device is activatable by the relay valve, wherein a valve which has a first connection and a second connection and a third connection is provided upstream of the trailer control module, wherein a second connecting line connecting the valve to the control valve device is connected to the second connection, wherein a third connecting line connecting the trailer control module to the valve is connected to the third connection, wherein a first connecting line which is attached to a first line arranged downstream of the relay valve is connected to the first connection.
The parking brake device for a utility vehicle can be in particular an electronic parking brake device for a utility vehicle.
The invention is based on the basic concept that it is sufficient for the activating of the parking brake function of the trailer control module to activate the control connection of the trailer control module for activating the parking brake device of a trailer of the utility vehicle for the driving mode and parking mode exclusively via the pressure prevailing behind the relay valve in the feed lines to the spring accumulators of the parking brake, i.e. essentially via the pressure from the spring accumulators of the parking brake of the utility vehicle. A connection to the control lines for activating the relay valve can therefore be omitted, and a simpler design is thereby possible. The line to the trailer control valve, which line can have different lengths for different vehicles or types of vehicle, is therefore no longer coupled to the control line of the relay valve, but rather to the spring accumulators. The control volume for the parking brake device can therefore have a constant value. The regulation of the parking brake device can therefore be simplified. In addition, the line length to the trailer control module can be varied with fewer restrictions.
The second connecting line connects the valve in particular directly to the control valve device (i.e., for example, a further valve is no longer arranged in the second connecting line between valve and control valve device).
The valve can be a 3/2-way valve.
Furthermore, it can be provided that the valve is a solenoid valve. This permits a precisely adjustable characteristic of the valve and reliable operation of the valve. In addition, the use or installation of valves of this type is cost-effective.
Furthermore, it is conceivable for the valve to be activated pneumatically. The requirement for the valve can be realized with said standard design. The use of standard components is cost-effective and, in addition, is also of advantage with regard to durability.
The valve can have a first control connection, wherein the first control connection is connected to the second connecting line by a first branch line. It is thereby possible to use the pressure in the second connecting line also for activating the valve. If the pressure in the second connecting line exceeds a specifiable or specified threshold value, the valve switches. It can be provided that the valve is kept in this position until the pressure which is present lies above the threshold value. In principle, however, it would also be conceivable for the valve to be kept stably in this position and for switching the valve to take place only by application of another control signal to another control connection of the valve.
Furthermore, it can be provided that the valve has a second control connection, wherein the second control connection is connected to the first connecting line by a second branch line. Analogously as in the first control connection, it is thereby possible also to use the pressure in the first connecting line for activating the valve. If the pressure in the first connecting line exceeds a specifiable or specified threshold value, the valve switches. It can be provided that the valve is kept in this position for as long as the pressure which is present lies above the threshold value. In principle, however, it would also be conceivable for the valve to be kept stably in this position and for switching of the valve to take place only by application of another control signal to another control connection of the valve.
In addition, it can be provided that the valve has at least one first switching state in which the first connection is connected to the third connection in such a manner that the pressure from the first connecting line is present at a control connection of the trailer control module. This affords the advantage that, in this state, the valve is connected exclusively pneumatically to that region of the parking brake device which lies downstream of the relay valve. This results in a decoupling of the line system of the parking brake device, said line system lying upstream of the relay valve and serving for activating the (bistable) control valve device and also the relay valve. The line length or length of the tubing is significantly reduced in comparison to current system, and also the design and the arrangement of the lines upstream of the relay valve are substantially simplified.
In particular, it can be provided that, at least in the first switching state, the first connecting line is connected to at least one spring accumulator of the parking brake of the utility vehicle, and therefore the first connecting line is imprinted by the at least one spring accumulator. It is thus possible to use the pressure which is present in any case in the spring accumulators of the utility vehicle pressure which is present for activating and actuating the trailer control module. This state is used in particular during parking of the utility vehicle.
The valve can have at least one second switching state in which the second connection is connected to the third connection in such a manner that the pressure from the second connecting line is present at a control connection of the trailer control module. The trailer control module can therefore be activated, specifically without the parking brake of the utility vehicle having to be released for this purpose. This is because, using this activation possibility, the trailer control module can be activated independently of the activation of the spring accumulators or independently of the pressure in the spring accumulators.
This is because, in the parking state, the intention is to be able to activate a function called “trailer test” with which the pressure signal to the trailer control module can be controlled separately. For this purpose, for the duration of the “trailer test”, the control line to the trailer control module for the parking brake function of the trailer is filled with compressed air (instead of being vented) while the spring accumulators continue to be vented. It can thus be checked whether the parking brake of the towing vehicle can by itself keep the vehicle combination of towing vehicle and trailer braked on the slope if the service brake action is no longer present at the trailer. For this purpose, during the trailer test, when the parking brake of the truck is applied, the service brake of the trailer is released by the control line of the trailer control valve being supplied with compressed air. The driver checks whether the vehicle combination rolls. Only if this is not the case can the vehicle combination be parked at this location.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.